This patent relates to protective packaging for large appliances such as washers, dryers and refrigerators. More particularly, this patent relates to an improved tubular-type protective corner post or side post that has a higher axial compression strength using the same amount (weight) of material as a conventional corner post.
Tubular type corner posts are used for holding axial compressive loads and protecting the corners of goods such as washers, dryers, refrigerators, dishwashers and stoves. Conventional tubular corner posts are made of a single sheet of paper wound into a convolute tube. Adhesive is used to bond the paper layers. Before the adhesive dries, the tube is shaped into the desired shape, typically one with a modified “L” shaped cross section to fit snugly between the corner of an appliance and the corner of the appliance container.
Various corner posts are described in the literature. Commonly owned Qiu U.S. Pat. No. 6,186,329, for example, describes a corner post made of multiple sheets of paper joined end to end and then wound around a mandrel so that the post wall has a strong-weak-strong profile in the transverse direction. In other words, a relatively weaker, less expensive grade of paper is sandwiched between layers of relatively stronger, costlier paper. The overall sheet, and the post, has a uniform thickness.
The failure mode of a corner post under axial compression is buckling. Therefore, the bending stiffness of the post structure is a critical parameter. It has been found that wall thickness and the physical characteristics of the material on the outside of the corner post wall determine bending stiffness.
The object of the present invention is to increase the bending stiffness of a corner post using the same amount (weight) of material as a conventional corner post.
Further and additional objects will appear from the description, accompanying drawings, and appended claims.